Fontan procedure
Encyclopedia
The Fontan procedure, or Fontan/Kreutzer procedure, is a palliative surgical procedure used in children with complex congenital heart defect
Congenital heart defect
A congenital heart defect is a defect in the structure of the heart and great vessels which is present at birth. Many types of heart defects exist, most of which either obstruct blood flow in the heart or vessels near it, or cause blood to flow through the heart in an abnormal pattern. Other...
s. It involves diverting the venous blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
from the right atrium
Right atrium
The right atrium is one of four chambers in the hearts of mammals and archosaurs...
to the pulmonary arteries
Pulmonary artery
The pulmonary arteries carry deoxygenated blood from the heart to the lungs. They are the only arteries that carry deoxygenated blood....
without passing through the morphologic pulmonary ventricle. It was initially described in 1971 by Dr Fontan and Dr Kreutzer separately as a surgical treatment for tricuspid atresia
Tricuspid atresia
Tricuspid atresia is a form of congenital heart disease whereby there is a complete absence of the tricuspid valve. Therefore, there is an absence of right atrioventricular connection. This leads to a hypoplastic or absent right ventricle....
.
Indications
The Fontan procedure has more recently been used in pediatric situations where an infant only has a single effective ventricle, either due to heart valveHeart valve
A heart valve normally allows blood flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart...
defects (e.g. tricuspid or pulmonary atresia
Pulmonary atresia
Pulmonary atresia is a congenital malformation of the pulmonary valve in which the valve orifice fails to develop. The valve is completely closed thereby obstructing the outflow of blood from the heart to the lungs. The pulmonary valve is located on the right side of the heart between the right...
) or an abnormality of the pumping ability of the heart (e.g. hypoplastic left heart syndrome
Hypoplastic left heart syndrome
Hypoplastic left heart syndrome , is a rare congenital heart defect in which the left ventricle of the heart is severely underdeveloped.-Causes:...
, hypoplastic right heart syndrome
Hypoplastic right heart syndrome
Hypoplastic right heart syndrome is a condition where the right atrium and right ventricle are underdeveloped.It is less common than hypoplastic left heart syndrome.In some cases it can be identified prenatally.It can be associated with aortic stenosis....
), or has complex congenital heart disease where a bi-ventricular repair is impossible or inadvisable.
Children with hypoplastic left heart syndrome have a single effective ventricle supplying blood to the lungs and the body (either from birth or after an initial surgery e.g. Norwood procedure
Norwood procedure
The Norwood Procedure is a surgery performed on the heart, the first successful use of the procedure was reported by Norwood and colleagues in 1981.Cardiopulmonary bypass is required.-Indications:...
). They are delicately balanced between inadequate blood supply to the lungs (causing cyanosis
Cyanosis
Cyanosis is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen. The onset of cyanosis is 2.5 g/dL of deoxyhemoglobin. The bluish color is more readily apparent in those with high hemoglobin counts than it is...
) and oversupply to the lungs (causing heart failure). In addition, the single ventricle is doing nearly twice the expected amount of work (because it has to pump blood for both lungs and body). As a result, these children can have trouble gaining weight, and are also vulnerable to decompensation
Decompensation
In medicine, decompensation is the functional deterioration of a previously working structure or system. Decompensation may occur due to fatigue, stress, illness, or old age. When a system is "compensated," it is able to function despite stressors or defects. Decompensation describes an inability...
in the face of otherwise minor illnesses (even a common cold). Sometimes medications (e.g. diuretics) can help them through this stage.
Therefore, when either they are large enough, and if the pressure in the pulmonary arteries is low enough, these children are referred for Fontan procedure commonly after 2 years of life.
Contraindications
After Fontan, blood must flow through the lungs without being pumped by the heart. Therefore children with high pulmonary vascular resistance may not tolerate a Fontan procedure. Often cardiac catheterizationCardiac catheterization
Cardiac catheterization is the insertion of a catheter into a chamber or vessel of the heart. This is done for both investigational and interventional purposes...
is performed to check the resistance before proceeding with the surgery. (This is also the reason a Fontan procedure cannot be done immediately after birth; the pulmonary vascular resistance is high in utero
In utero
In utero is a Latin term literally meaning "in the womb". In biology, the phrase describes the state of an embryo or fetus. In legal contexts, the phrase is used to refer to unborn children. Under common law, unborn children are still considered to exist for property transfer purposes.-See also:*...
and takes months to drop.)
Types
There are three different types of Fontan procedure:- Atriopulmonary connection (the original) Described by Fontan and Kreutzer.
- Intracardiac total cavopulmonary connection (lateral tunnel)
- Extracardiac total cavopulmonary connection
Approach
The Fontan is usually done as a two staged repair.The first stage, also called a Bidirectional Glenn procedure or Hemi-Fontan (see also Kawashima procedure
Kawashima procedure
The Kawashima procedure is used for congenital heart disease with a single effective ventricle and an interrupted inferior vena cava . It was first performed in 1978 and reported in 1984.-Procedure:...
), involves redirecting oxygen-poor blood from the top of the body to the lungs. That is, the pulmonary arteries are disconnected from their existing blood supply (e.g. a shunt created during a Norwood procedure
Norwood procedure
The Norwood Procedure is a surgery performed on the heart, the first successful use of the procedure was reported by Norwood and colleagues in 1981.Cardiopulmonary bypass is required.-Indications:...
, a patent ductus arteriosus
Patent ductus arteriosus
Patent ductus arteriosus is a congenital disorder in the heart wherein a neonate's ductus arteriosus fails to close after birth. Early symptoms are uncommon, but in the first year of life include increased work of breathing and poor weight gain...
, etc.). The superior vena cava
Superior vena cava
The superior vena cava is truly superior, a large diameter, yet short, vein that carries deoxygenated blood from the upper half of the body to the heart's right atrium...
(SVC), which carries blood returning from the upper body, is disconnected from the heart and instead redirected into the pulmonary arteries. The inferior vena cava
Inferior vena cava
The inferior vena cava , also known as the posterior vena cava, is the large vein that carries de-oxygenated blood from the lower half of the body into the right atrium of the heart....
(IVC), which carries blood returning from the lower body, continues to connect to the heart.
At this point, patients are no longer in that delicate balance, and the single ventricle is doing much less work. They usually can grow adequately, and are less fragile. However, they still have marked hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
(because of the IVC blood that is not fed into the lungs to be oxygenated). Therefore most patients are referred for another surgery.
The second stage, also called Fontan completion, involves redirecting the blood from the IVC (inferior vena cava) to the lungs as well. At this point, the oxygen-poor blood from upper and lower body flows through the lungs without being pumped (driven only by the pressure that builds up in the veins). This corrects the hypoxia, and leaves the single ventricle responsible only for supplying blood to the body.
Post-operative complications
In the short term, children can have trouble with pleural effusionPleural effusion
Pleural effusion is excess fluid that accumulates between the two pleural layers, the fluid-filled space that surrounds the lungs. Excessive amounts of such fluid can impair breathing by limiting the expansion of the lungs during ventilation.-Pathophysiology:...
s, fluid building up around the lungs. This can require a longer stay in the hospital for drainage with chest tube
Chest tube
A chest tube is a flexible plastic tube that is inserted through the side of the chest into the pleural space. It is used to remove air or fluid , or pus from the intrathoracic space...
s. To address this risk, some surgeons make a fenestration (a small hole) from the venous circulation into the atrium. When the pressure in the veins is high, some of the oxygen-poor blood can escape through the fenestration to relieve the pressure. However, this results in hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
, so the fenestration may eventually need to be closed by an interventional cardiologist.
In the long term, children can have trouble with atrial flutter
Atrial flutter
Atrial flutter is an abnormal heart rhythm that occurs in the atria of the heart. When it first occurs, it is usually associated with a fast heart rate or tachycardia , and falls into the category of supra-ventricular tachycardias. While this rhythm occurs most often in individuals with...
and atrial fibrillation
Atrial fibrillation
Atrial fibrillation is the most common cardiac arrhythmia . It is a common cause of irregular heart beat, identified clinically by taking a pulse. Chaotic electrical activity in the two upper chambers of the heart result in the muscle fibrillating , instead of achieving coordinated contraction...
because of scarring in the atrium, especially if the connection of IVC to pulmonary arteries involved an intracardiac baffle (instead of an extracardiac conduit). This sometimes requires treatment such as radiofrequency ablation
Radiofrequency ablation
Radio frequency ablation is a medical procedure where part of the electrical conduction system of the heart, tumor or other dysfunctional tissue is ablated using the heat generated from the high frequency alternating current to treat a medical disorder...
. There are other long-term risks, including protein-losing enteropathy and chronic renal insufficiency, although understanding of these risks is still incomplete. Some patients require long-term blood thinners.
The Fontan procedure is palliative, not curative. But in many cases it can result in normal or near-normal growth, development, exercise tolerance, and good quality of life. In most cases, patients will eventually require heart transplantation
Heart transplantation
A heart transplant, or a cardiac transplantation, is a surgical transplant procedure performed on patients with end-stage heart failure or severe coronary artery disease. As of 2007 the most common procedure was to take a working heart from a recently deceased organ donor and implant it into the...
.
External links
- Overview of single ventricle lesions from Cincinnati Children's Heart Center